Breeding, Reproduction and Herd Improvement
This domain tests heat detection, artificial insemination timing, gestation, calving interval and genetic improvement. Good breeding management decides how quickly a herd becomes productive.
Core facts
- Oestrus cycle: about 18–24 days, commonly 21 days. Heat duration: about 12–18 hours.
- AI timing: use the AM–PM rule. If heat is first seen in the morning, inseminate the same evening; if seen in the evening, inseminate the next morning.
- Gestation: about 280 days for cattle and 310 days for buffaloes. Service period target: 60–90 days. Calving interval: about 12–13 months in cattle and 15–16 months in buffaloes.
- Pregnancy diagnosis: about 45–60 days after breeding. Use AI with semen from a proven bull, maintain breeding records and avoid inbreeding.
Worked example
A cow is first seen in heat at 6 a.m. on 1 June. By the AM–PM rule, inseminate that evening. If conception occurs, calving is expected around 8 March, because 1 June plus 280 days falls in early March. Record the insemination date, bull/semen code and repeat heat date.
Traps
Do not inseminate too early or too late, ignore silent heat, repeat AI without checking pregnancy, or use an unproven bull repeatedly. Do not confuse heat with discharge or restlessness alone.